A systematic review, meta-analysis, and meta-regression of the impact of diurnal intermittent fasting during Ramadan on glucometabolic markers in healthy subjects

Aim: Studies on the effect of Ramadan diurnal intermittent fasting (RDIF) on glucometabolic markers have yielded conflicting results. We conducted a meta-analysis to estimate the effect size for changes in glucometabolic markers in healthy, non-athletic Muslims during Ramadan, and to assess the effect of variable covariates using meta-regression. Methods: CINAHL, Cochrane, EBSCOhost, EMBASE, Google Scholar, ProQuest Medical, PubMed/MEDLINE, ScienceDirect, Scopus, and Web of Science databases were searched from date of inception to January 2020. The glucometabolic markers analyzed were: fasting glucose (FG), insulin, insulin resistance (HOMA-IR), leptin, and adiponectin. Results: We identified seventy-two studies (3134 participants in total) that were conducted in 22 countries between 1982 and 2020. RDIF-induced effect sizes for the glucometabolic markers were: FG (no. of studies K = 61, number of subjects N = 2743, Hedges' g = -0.102, 95% CI: -0.194, -0.01); serum insulin (K = 16, N = 648, Hedges' g = 0.030 95% CI: -0.165, 0.226); HOMA-IR (K = 10, N = 349, Hedges' g = -0.012, 95% CI: -0.274, 0.250); leptin (K = 13, N = 442, Hedges' g = -0.010, 95% CI: -0.243, 0.223); and adiponectin (K = 11, N = 511, Hedges' g = 0.034, 95% CI: - 0.227, 0.296). Conclusion: RDIF imposes no adverse metabolic impacts, and might help in improving some glucometabolic markers in healthy subjects. (C) 2020 Elsevier B.V. All rights reserved.